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Discussion Starter #1
2012 Xterra. Heater temp control problem. It will make the air hot when you go full clockwise into the solid red area on the dial (abt 5 o'clock) If you go even one click back counter clockwise out of the solid red (abt 4 o'clock) you can hear the gate open up and the hot air turns barely warm. So my choice is too hot, or not hot enough.

Have not been into this area of the X before so I don't know how the control of the heat/cool gate works. Seems to open and close but just no control over the temperature. Does this even with the A/C selected.

Even if you do not know the solution can you tell me where the motor is that drives the gate? I have the dash apart and can't see anything move when I turn the temp control.
 

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Discussion Starter #5
I think I have a better terminology of the parts after quite a few searches. The part that I think is the problem is the "heater blend door actuator". Have not yet found good info on how to replace it or exactly where it is located.

The other possibility is the temperature control on the dash which is easy to get to. I found one on eBay for a good price and will try that first.

If anyone has info on replacing the actuator I would appreciate it. :dontknow:
 

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Discussion Starter #7
your truck should still be under warranty no? idk why you're trying to fix it yourself..just bring it to the dealer
3 year / 36,000 mile and I am at 40k+ :-(

But on the brighter side; this is the first thing that has had a problem.
 

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Discussion Starter #10
I am going to bump this back up. Still no solution but I have learned to deal with it. Found out it does the same thing with the A/C. If you go full cold it works but if you move it even a little clockwise it is not cold enough. I did get the control head for the dash and it did not change the problem.

Anyone else deal with this?
 

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I thought 60 month, 60K on bumper to bumper and 120 month / 100K Powertrain was more common...
 

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In the service manual MTC.PDF, there is very complete troubleshooting of the air mix door system.

Your first task will be to determine if the problem is in the air mix door motor position sensor or in the controller. In the manual there are some voltage and resistances that you can check with a simple multimeter.
 

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Discussion Starter #13
In the service manual MTC.PDF, there is very complete troubleshooting of the air mix door system.

Your first task will be to determine if the problem is in the air mix door motor position sensor or in the controller.
I replaced the controller. Not expensive and easy to do.
 

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Discussion Starter #15
Did replacing the controller fixed your issue ?
No. :confused:

I ran through the diagnostics in the manual today. What I know for sure:
1. The air mix door motor is working. It can move the door to hot and cold.
2. The 5 volt reference (VREF) is 4.8v which is good since the mode door uses the same reference and works fine.
3. On pin 22 of the controller the Position Balanced Resistor (PBR) at the door motor goes between .4 and 4.5 volts at each end but in the middle it continually "hunts". It oscillates back and forth over about a one volt range. So it is there and it does read the position but will not stabilize in the mid range.

If I had not already replaced the controller the readings would lead me to replacing it. The troubleshooting only has good / no good options. No option for sort of works but incorrectly or fails to stabilize. :(

The unknown is not actually seeing the air mix motor assembly in operation. Suppose it could be a physical linkage issue. About all I accomplished was eliminating the motor and PBR.
 
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